The Mark Morris Dance Group, which has made this city's Zellerbach Hall its West Coast home since 1987, completed its 200th dance performance here just before opening its version of Handel's pastoral opera "Acis and Galatea" recently—the eighth world premiere the company has offered to Cal Performances, which co-commissioned it. It was, along with Handel's "L'Allegro, il Penserato ed il Moderato," the most singularly beautiful creation of the MMDG I have seen.